gms | German Medical Science

The WHO classification of human meningiomas distinguishes between three histological malignancy grades related to risk of recurrence. Most tumors are graded based on mitotic index, a method of limited value due to substantial within-grade variation in recurrence risk, subjective assessment of grading criteria and poor reproducibility. To improve the diagnostics of human meningiomas this study investigated the prognostic value of phosphohistone-H3 (PHH3) proliferation index (PI) in 160 patients, and compared the reliability with the conventional mitotic index and the established biomarker MIB-1. Proliferative activity was determined by standardized immunohistochemistry on tissue microarrays and related to recurrence-free survival. All three proliferation assessment methods were significantly associated with WHO grade. The optimal cutoff values for recurrence prediction were 3% for the MIB-1 PI and 0.5% for the PHH3 PI. Increased PHH3 PI was significantly associated with recurrence-free survival in univariate Cox hazard analysis (P = 0.011) and remained an independent predictor in multivariate analysis (P = 0.005). Mitotic index and MIB-1 PI did not reach significance. PHH3 immunostaining allowed for the easiest, fastest and most objective assessment of proliferation, and proved to be the most accurate and reliable method for predicting recurrence in meningioma patients compared with the current established methods. For this reason, incorporating PHH3 PI into the diagnostics of meningiomas should be considered to ensure optimal treatment of these patients.